Science: Now they're smiling by the bournes: When streams in southern England began to run dry, water companies were blamed. But other, greater forces may have been at work, says Michael Price

THERE HAS been something different about many villages in southern England this spring: running water. For three years or so some of the most affluent parts of the country have been deprived of that hallmark of up-market property - a village stream. Last year there were dire warnings that these streams, and their wildlife, were being destroyed by those modern oppressors of nature and the middle-classes, the water companies. What has brought about the revival? And what was the real reason for the disappearance of the streams?

In dry weather, streams can keep flowing only if there is some natural store to maintain flow. In south-east England that store is ground water in permeable rocks such as 'the Chalk', the belt that stretches from the white cliffs at Dover as far as Wiltshire and up to Lincolnshire and Yorkshire.

Rainfall soaks into these permeable rocks, and 'fills up' the storage space within them until the water table reaches the ground surface in one or more places. This generally happens where the ground is low, usually in a valley. Water flowing naturally from the Chalk sustains the flow of many of the streams that do so much to enhance the landscape (and the property values) of the South-east. The flow from the ground continues as long as the water table remains above ground level. If it is always above ground, the stream is said to be perennial.

Until the advent of piped supplies many settlements grew up around sources of water such as wells and streams. Different areas of the country have their own names for streams; in southern England, they are bourns or bournes. These names, like the Scottish burn, derive from the Old English word burna meaning a brook or spring.

It was natural that these sources should figure in place names. So we find many place names, some ancient and some less so, that contain the word bourn or bourne. Examples are Pangbourne, where the Pang flows into the Thames; and Lambourn (of racehorse fame) on the Berkshire Downs.

Rainfall in England is spread throughout the year, but in spring and summer the demands of growing plants allow little of that rain through to the rocks beneath. The soil dries out and absorbs any rain that falls on it, until autumn, when plant growth slows down. This means water recharges the rocks for only part of the year, but is draining from them to the streams all year round. As a result the water table rises and falls seasonally; typically it reaches a maximum in late winter, and is at its lowest around October or November.

In some valleys it is above the ground surface in the lower part of the valley throughout the year, so this part of the valley will have a perennial stream; but in the upper part of the valley it is above ground only during the winter and spring. The stream in the upper part of the valley is said to be intermittent, and the highest point at which it flows throughout the year is the perennial head. However, streams are only perennial in the way that volcanoes are extinct - until the time when something changes.

The water table in the Chalk rises and falls more than in most rocks. Intermittent streams are therefore a particular feature of the Chalk country. Because they are bournes that flow mainly in winter they are called, not unreasonably, winterbournes.

Many 'bournes' are actually winterbournes for at least part of their length, and many place names with the bourne element lie on or near winterbournes, although only a few use the full epithet: there is a clutch in Dorset - Winterbourne Kingston, Winterbourne Abbas, and so on.

A source of water as abundant as that in the Chalk is attractive not just to fish, ducks and residents. For decades many of the water companies that serve the area have taken water from the Chalk to supply their consumers. When you take water out of a store the level will fall. When that store is as large as the Chalk, the fall will be small, but nevertheless the water table will be lower in the vicinity of the borehole. The fall may be enough to reduce the flow of a winterbourne, dry it up completely, or make it flow for a shorter period each year. The perennial head may migrate down the valley; this has happened, for example, to the Candover Stream in Hampshire, where the perennial head used to be a few hundred metres above Totford. Since the opening of a pumping station at Totford in 1952, it is a few hundred metres below it.

Equally, if less water enters the ground, there will be less to flow out. Between spring 1988 and spring 1992 south-east England experienced a remarkable drop in rainfall - only about 80 per cent of the long-term average, in an area where rainfall is low anyway. Much of the shortfall occurred in winter, when it would normally provide recharge to ground water.

To many residents these 'winter droughts' were not as noticeable as the disappearance of their local streams. Hearing that some rivers were being affected by pumping, villagers whose streams were disappearing looked around for a water company to blame.

The newly formed National Rivers Authority (NRA) did not always help matters. Some of its media pronouncements seemed to exaggerate the case of over-pumping, culminating in a news item in which the NRA apologised for switching on the Candover scheme - where water is pumped from the ground to augment the flow of the Candover Stream and the River Itchen in dry weather - on the basis that ground-water abstraction was bad for the environment.

The generally wet summer, autumn and early winter led to Chalk water tables rising dramatically this year, and the winterbournes are flowing again. But residents of winterbourne villages would do well to note one other feature common on the Chalk downs. Dry valleys show where rivers once flowed, testifying to changes in climate over which we have had no control. The bournes have come back this spring; but if they are not always with us, it may not necessarily be the water companies that are to blame.

The writer is senior lecturer in hydrogeology at the University of Reading.

(Graphics omitted)

Start your day with The Independent, sign up for daily news emails
Sport
England's women celebrate after their 3rd place play-off win against Germany
Women's World CupFara Williams converts penalty to secure victory and bronze medals
Arts and Entertainment
Ricardo by Edward Sutcliffe, 2014
artPortraits of LA cricketers from notorious suburb go on display
News
newsHillary Clinton comments on viral Humans of New York photo of gay teenager
Arts and Entertainment
The gang rape scene in the Royal Opera’s production of Gioachino Rossini’s Guillaume Tell has caused huge controversy
music
ebooks
ebooksAn introduction to the ground rules of British democracy
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Sales Administrator - Spanish Speaking

£17000 - £21000 per annum: Recruitment Genius: This is a fantastic opportunity...

Recruitment Genius: Sales Administrator - German Speaking

£17000 - £23000 per annum: Recruitment Genius: This is a fantastic opportunity...

Recruitment Genius: Sales Administrator - Japanese Speaking

£17000 - £23000 per annum: Recruitment Genius: If you are fluent in Japanese a...

Recruitment Genius: Graphic Designer - Immediate Start

£16000 - £25000 per annum: Recruitment Genius: This is a fantastic opportunity...

Day In a Page

The Greek referendum exposes a gaping hole at the heart of the European Union – its distinct lack of any genuine popular legitimacy

Gaping hole at the heart of the European Union

Treatment of Greece has shown up a lack of genuine legitimacy
Number of young homeless in Britain 'more than three times the official figures'

'Everything changed when I went to the hostel'

Number of young homeless people in Britain is 'more than three times the official figures'
Compton Cricket Club

Compton Cricket Club

Portraits of LA cricketers from notorious suburb to be displayed in London
London now the global money-laundering centre for the drug trade, says crime expert

Wlecome to London, drug money-laundering centre for the world

'Mexico is its heart and London is its head'
The Buddhist temple minutes from Centre Court that helps a winner keep on winning

The Buddhist temple minutes from Centre Court

It helps a winner keep on winning
Is this the future of flying: battery-powered planes made of plastic, and without flight decks?

Is this the future of flying?

Battery-powered planes made of plastic, and without flight decks
Isis are barbarians – but the Caliphate is a dream at the heart of all Muslim traditions

Isis are barbarians

but the Caliphate is an ancient Muslim ideal
The Brink's-Mat curse strikes again: three tons of stolen gold that brought only grief

Curse of Brink's Mat strikes again

Death of John 'Goldfinger' Palmer the latest killing related to 1983 heist
Greece debt crisis: 'The ministers talk to us about miracles' – why Greeks are cynical ahead of the bailout referendum

'The ministers talk to us about miracles'

Why Greeks are cynical ahead of the bailout referendum
Call of the wild: How science is learning to decode the way animals communicate

Call of the wild

How science is learning to decode the way animals communicate
Greece debt crisis: What happened to democracy when it’s a case of 'Vote Yes or else'?

'The economic collapse has happened. What is at risk now is democracy...'

If it doesn’t work in Europe, how is it supposed to work in India or the Middle East, asks Robert Fisk
The science of swearing: What lies behind the use of four-letter words?

The science of swearing

What lies behind the use of four-letter words?
The Real Stories of Migrant Britain: Clive fled from Zimbabwe - now it won't have him back

The Real Stories of Migrant Britain

Clive fled from Zimbabwe - now it won’t have him back
Africa on the menu: Three foodie friends want to popularise dishes from the continent

Africa on the menu

Three foodie friends want to popularise dishes from the hot new continent
Donna Karan is stepping down after 30 years - so who will fill the DKNY creator's boots?

Who will fill Donna Karan's boots?

The designer is stepping down as Chief Designer of DKNY after 30 years. Alexander Fury looks back at the career of 'America's Chanel'